Downhole bridge plugs and packers are well known in the industry, each having been extensively used over a substantial number of years. Each type of device includes a seal member and each generally includes an anchoring arrangement. The seal and the anchoring arrangement each have to be set for the device to work properly. While bridge plugs and Packers are distinct devices, at a conceptual level many are similar. With respect to the method disclosed in this application, they are nearly the same as the method works equivalently for both. For the sake of simplicity then, reference will be made to “Packers” hereinafter, but it will be understood that both are intended. Locationally fixing (anchoring) the packer to the wellbore is typically accomplished with a plurality of slips. In some packers the slips start as a slip ring mounted around a conical member. As the packer is actuated the slip ring is forced axially over a conical member thereby breaking the slip, at designated fracture points, into a plurality of slips. The plurality of slips wedge between the packer and an inside surface of the wellbore. Sealing of the packer within the wellbore is typically accomplished with at least one sealing element. The at least one sealing element, when actuated, expands radially outwardly to sealingly engage with the inner surface of the wellbore. The slips and the sealing elements of a packer are commonly actuated relatively simultaneously.
As such, once actuation of a packer is initiated the process continues until the actuation of both the slips and the at least one sealing element is completed. There are a variety of triggers used to initiate actuation of a packer that are well known in the industry.
Also common in the industry are hydrostatic setting tools also known as actuators. Hydrostatic setting tools use hydrostatic pressure available downhole to drive the actuation and setting of the slips and the at least one sealing element. Such systems are known in the industry an example of which is described in U.S. Pat. No. 4,353,842, which is incorporated herein in its entirety by reference. As described in U.S. Pat. No. 4,353,842 fluid under hydrostatic pressure urges movement of an actuator that actuates the slips and the at least one sealing element.
In order to control a rate of actuation in the packer it is common to employ mechanisms to slow the setting of the slips and actuation of the at least one sealing element. Some such systems employ a fluid metering system to control the rate porting the fluid through small orifices. These metering systems slow the setting of the packer somewhat, but not as much as may be desired to optimize the seating and longevity of the sealing element. Additionally, the timing of the metering system is set prior to running the apparatus downhole and as such is not receptive to changes that may be desirable upon changing well formation conditions.
Accordingly, the art may be receptive to simple downhole packers that have controllable setting rates.